1. Technical Field
The present invention relates to a vehicle portable device and an information communication system, particularly to a vehicle portable device and an information communication system, for notifying a user of information on a vehicle.
2. Related Art
Conventionally, there is proposed that a user can check pieces of vehicle information, such as a vehicle status, or operate the vehicle using mobile terminals, such as a mobile phone.
For example, U.S. Pat. No. 7,821,383 proposes that a vehicle portable device (a portable FOB) possessed by a user conducts middle-range wireless communication with an in-car communication device, conducts short-range wireless communication with a portable communication terminal, and relays transmission of a menu from the in-car communication device to the portable communication terminal and transmission of a menu selection result from the portable communication terminal to the in-car communication device, thereby operating the vehicle from the portable communication terminal.
For example, Japanese Unexamined Patent Publication No. 2007-46395 proposes that a base unit incorporated in the vehicle and the vehicle portable device (an extension handset) conduct the wireless communication with each other to control a vehicle key, the portable communication terminal is connected to the extension handset in a wired manner, information on a setting change is transmitted to the base unit through the extension handset when a user operates a setting change screen displayed on the portable communication terminal, thereby changing the setting of in-car devices.
For example, Japanese Unexamined Patent Publication No. 2001-288941 proposes that an information device transmits and receives various pieces of information to and from the vehicle portable device for locking and unlocking a door of the vehicle and an in-car device that performs various kinds of control to the vehicle by short-range wireless communication, such as Bluetooth (registered trademark), and the vehicle portable device and the in-car device transmit and receive various pieces of information to and from each other by short-range wireless communication, such as Bluetooth.
Japanese Unexamined Patent Publication No. 2010-38684 proposes that a direction or a distance between the vehicle and the vehicle portable device is detected according to received signal intensity between the vehicle and the vehicle portable device and the direction in which the vehicle exists or the distance to the vehicle is displayed on the vehicle portable device.
Japanese Unexamined Patent Publication No. 2008-144517 proposes that the intensity of the signal transmitted from the vehicle portable device (an electronic key) onto a security apparatus on the vehicle side is strengthened. In the proposal of Japanese Unexamined Patent Publication No. 2008-144517, the electronic key transmits an ACK signal having a reference output level when initially receiving a WAKE signal from the security device on the vehicle side, and the electronic key transmits the ACK signal having an output level higher than the reference output level when the security device transmits the WAKE signal again.
Conventionally, because a dedicated algorithm is used in the communication between the vehicle and the vehicle portable device, a third party hardly analyzes the signal to learn a communication content even if the third party intercepts the communication content.
However, in the wireless communication, such as Bluetooth, which is opened to the public, possibly the malicious third party learns the communication content when intercepting the communication content. Particularly, possibly a theft of the vehicle is induced when pieces of high-secret-level information, such as a parking position, leak to the malicious third party.